Tubular endoprosthesis or “stents” have been suggested for dilating or otherwise treating stenoses, occlusions, and/or other lesions within a patient's vasculature or other body lumens. For example, a self-expanding stent may be maintained on a catheter in a contracted condition, e.g., by an overlying sheath or other constraint, and delivered into a target location, e.g., a stenosis within a blood vessel or other body lumen. When the stent is positioned at the target location, the constraint may be removed, whereupon the stent may automatically expand to dilate or otherwise line the vessel at the target location. Alternatively, a balloon-expandable stent may be carried on a catheter, e.g., crimped or otherwise secured over a balloon, in a contracted condition. When the stent is positioned at the target location, the balloon may be inflated to expand the stent and dilate the vessel.
Vascular stenoses, e.g., within arteries supplying the heart, can lead to hypoflow conditions in the vessel, which may cause ischemia and/or infarction of the organ being supplied by that vessel, e.g., the heart. Sometimes, a stenosis or other lesion may occur at an ostium or bifurcation, i.e., where a branch vessel extends from a main vessel or trunk. In such situations, it may be difficult to visualize the lesion and/or accurately position a stent within the ostium and/or branch vessel.
Often, when the stent is deployed in such anatomy, one end of the stent may extend out from the ostium into the main vessel, e.g., into the aorta from a coronary artery, common carotid artery, or peripheral artery. Such a position of the stent may cause difficulty in future endoluminal interventions, e.g., reentering the branch vessel, which may require recrossing the stent. In addition, there may be risk that the end of the stent extending from the ostium may cause damage to neighboring structures, such as aortic valve leaflets adjacent to the ostium of a coronary vessel. Furthermore, there may be little or no contact between the stent and the wall of the ostium, which may result in suboptimal treatment of the lesion.
To address these problems, it has been suggested to over-expand or flare the end of the stent extending into the main vessel, e.g., to direct the end of the stent against or closer to the wall of the ostium. Thereafter, it may be easier to recross the stent in case future endovascular study or intervention is required. In addition, in the case of coronary stents, flaring the end of the stent extending into the aorta may also move the end further from the aortic lumen and decrease the risk of damage to the aortic leaflets. Furthermore, direct contact or closer positioning of the stent to the wall of the ostium may result in improved treatment of the lesion.
Accordingly, apparatus and methods for flaring and/or otherwise expanding stents or other prostheses would be useful.